Roof Ridge Different Heights

Roof pitch calculator results explained.

Roof ridge different heights.

In certain sections of the house the roof overlaps the high and low sections. The only way to eliminate that is to block off each level of attic area. Unless its separated from the main attic space. I am trying to create the roof for a complex house with 10 and 12 walls.

The roof with the lower eave height would require a roof slope pitch greater that the roof with the higher eave height. 3 difference is our rule of thumb. To scribe the roof angle on the ridge a length of stock is leveled over from the common rafters and a 2 by scrap is set against the sleepers. The top of the ridge beam m y.

Another by product of this roof configuration is varying soffit heights and widths which require further design decisions. I have attached pictures of an example of one of the sections i am trying to create the roof for. In a typical saltbox house one side of the roof covers the top floor of the house while the other side slopes all the way down to the ground floor. A 1 in 12 roof pitch roof rises 1 inch for every 12 inches of run.

The reason being is the the higher long peak ridge vent end up drawing air through the lower smaller ridge vents on the peak. The pitch of a roof determines the height of the ridge board that runs the length of the house. The most common parameter is to maintain an equal ridge height over building sections with differing spans. Rafters are nailed to the ridge board and run down to overhang the exterior wall.

To keep the ridge line centered on the structure and have 2 eaves at different heights with identical overhangs you would have to have 2 different roof slopes. Carpenters measure roof pitch as inches of rise per 12 inches of run. Since the beam height is 1 taller then the 8 wall height that gives you a triangle with a 7 12 pitch with a 1 rise and a run of 20 9 16 and a rafter length of 23 13 16. Air is like water.

Therefore that will move your ridge from the center of the 40 3 1 2 span. To maintain a consistant ridge height in these situations the roof pitch must be adjusted. The saltbox roof has two sides of different lengths which slope outwards from a central ridge. My roof guy said ridge vents shouldn t be installed at different heights.

To determine the y height measure from the bird s mouth up the calculated slope x in 12 to the top of the rafter. I cannot seem to make this work. Even at a 3 difference in height the ends of the lower ridge vent will become intakes for the higher vents. This roof is used in asymmetrical houses where the upper floor doesn t completely overlay the lower.

For example along the long peak and then on the gables that blend into the roof at a lower level than the highest long peak.